A chlor-alkali industrial salt mud washing and dechlorination device and process

Abstract

A chlor-alkali industrial salt mud washing and dechlorination device and process, firstly, the chlor-alkali industrial salt mud is sent into a stirring and dissolving kettle, and sodium chloride concentrate and washing circulating liquid are circulated to the stirring and dissolving kettle for stirring; the stirred and dissolved material is sent into a flocculation kettle to add a coagulant aid PAM, and then sent into a clarification sedimentation tank for free sedimentation, the settled solid matter is sent into a first centrifuge for solid-liquid separation, the supernatant and the centrifuge liquid are sent into a first circulation tank, part of the sodium chloride concentrate in the first circulation tank is circulated to the stirring reactor, and the remaining part is sent to the salting section for recycling; the separated solid matter is sent into a washing machine, and the washing circulating liquid in the second circulation tank is used for washing and dechlorination, the solid matter is sent into a second centrifuge, the washing liquid and the centrifuge liquid are sent into a second circulation tank, the solid matter is landfilled or further recycled, part of the material in the second circulation tank is circulated to the stirring and dissolving kettle, and the remaining part is circulated to wash the material; the present invention realizes the washing and dechlorination of salt mud and improves the quality of resource recovery products.

Description

Technical Field

[0001] The invention relates to the technical field of salt mud disposal in chlor-alkali industry, and in particular to a device and process for washing and dechlorinating salt mud in chlor-alkali industry. Background Art

[0002] Salt mud is a solid waste generated during the refining process of raw salt in the chlor-alkali industry. With the development of the chlor-alkali industry, the problem of salt mud disposal has become increasingly prominent. The disposal method of salt mud in the chlor-alkali industry is basically limited to solid-liquid separation by filtration to reduce the volume of salt mud. The salt mud after filtration is stored or landfilled.

[0003] Chlor-alkali industrial salt mud is a mixture of inorganic salts. Its composition varies depending on the industrial salt or brine used in different places, but its main components are calcium carbonate, calcium sulfate, magnesium carbonate, sodium chloride and clay. In addition, it also contains a small amount of barium sulfate, ferric oxide and aluminum oxide. Among them, the water-soluble salt is mainly sodium chloride. According to literature reports, the content of sodium chloride in salt mud is 5-50% (dry basis), which is obviously higher than the landfill requirements of Class I landfills (the total amount of water-soluble salt in the solid of Class I landfills is less than 2% (dry basis)). If the content of sodium chloride in salt mud is not further reduced, it can only be landfilled as hazardous waste, which will inevitably increase the cost of salt mud disposal.

[0004] The large-scale storage or landfill disposal of salt mud not only occupies a large amount of land, but also causes great pollution to the environment. The comprehensive utilization of chlor-alkali industrial salt mud is mainly to recover the calcium and magnesium ions therein. The research team previously disclosed a chlor-alkali industrial salt mud resource comprehensive disposal system (CN 113003771 B) to recover the calcium and magnesium ions in the salt mud. In the process of comprehensive utilization of salt mud, the presence of sodium chloride will affect the quality of subsequent products. In summary, it is very necessary to wash and remove sodium chloride before landfilling or comprehensive utilization of chlor-alkali industrial salt mud. However, salt mud is generally washed with a large amount of seawater, which not only produces a large amount of wastewater, but also causes a waste of sodium chloride resources. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a chlor-alkali industrial salt mud washing and dechlorination device and process, which can reduce the sodium chloride content in the chlor-alkali industrial salt mud to meet the requirements of landfill or recovery of calcium and magnesium ions, and realize the resource recovery and utilization of sodium chloride.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A chlor-alkali industrial salt mud washing and dechlorination device comprises a stirring and dissolving kettle 2, wherein the upper feed port of the stirring and dissolving kettle 2 is connected to the outlet of a screw feeder 1; the washing circulating liquid inlet of the stirring and dissolving kettle 2 is connected through a second circulating pump 15 and a second circulating tank 14, and the second circulating tank 14 is connected to the washing liquid inlet of a washing machine 12 through a third circulating pump 19; the pure water inlet of the stirring and dissolving kettle 2 is connected to a first storage tank 16 through a first metering pump 18, and the first storage tank 16 is connected to the washing liquid inlet of the washing machine 12 through a third metering pump 17; the bottom outlet of the stirring and dissolving kettle 2 is connected through a first outlet The material pump 3 is connected to the feed port of the flocculation kettle 6, the upper liquid inlet of the flocculation kettle 6 is connected to the second storage tank 4 through the second metering pump 5, and the bottom outlet of the flocculation kettle 6 is connected to the upper inlet of the clarification sedimentation tank 8 through the second discharge pump 7; the top liquid outlet of the clarification sedimentation tank 8 is connected to the first inlet of the first circulation tank 9, the bottom discharge port of the clarification sedimentation tank 8 is connected to the first centrifuge 10, the liquid outlet of the first centrifuge 10 is connected to the second inlet of the first circulation tank 9, the bottom outlet of the first circulation tank 9 is connected to the return port of the stirring and dissolving kettle 2 through the first circulation pump 11, and the bottom discharge may enter the salting section for reuse;

[0008] The solid discharge at the bottom of the first centrifuge 10 is landfilled or used to recover calcium and magnesium. The solid discharge at the bottom may be connected to a washing machine 12. The washing liquid outlet of the washing machine 12 is connected to the first inlet of a second circulation tank 14. The solid outlet of the washing machine 12 is connected to a second centrifuge 13. The liquid outlet of the second centrifuge 13 is connected to the second inlet of the second circulation tank 14. The solid discharge at the bottom of the second centrifuge 13 is landfilled or used to recover calcium and magnesium.

[0009] The process of using the chlor-alkali industrial salt mud washing and dechlorination device comprises the following steps:

[0010] The first step is to feed the chlor-alkali industrial salt mud into the stirring and dissolving kettle 2 through the screw feeder 1, start the stirring device of the stirring and dissolving kettle 2, and at the same time, feed part of the sodium chloride concentrate in the first circulation tank 9 into the stirring and dissolving kettle 2 through the first circulation pump 11, and feed part of the washing circulation liquid in the second circulation tank 14 into the stirring and dissolving kettle 2 through the second circulation pump 15; in addition, according to the water balance calculation, a certain amount of pure water is added from the first storage tank 16 into the stirring and dissolving kettle 2 through the first metering pump 18;

[0011] In the second step, the fully dissolved material is discharged from the bottom of the stirring and dissolving tank 2 and sent to the flocculation tank 6 through the first discharge pump 3. At the same time, the cationic PAM solution in the second storage tank 4 is sent to the flocculation tank 6 through the second metering pump 5. The stirring device of the flocculation tank 6 is started, and the rapid stirring is performed for 5 minutes and the slow stirring is performed for 25 minutes. The flocculated material is discharged from the bottom of the flocculation tank 6 and sent to the clarification sedimentation tank 8 through the second discharge pump 7 for free sedimentation. The supernatant after sedimentation is discharged from the top of the clarification sedimentation tank 8 and flows into the first circulation tank 9 by gravity. The settled solid material is discharged from the bottom of the clarification sedimentation tank 8 and sent to the first centrifuge 10 for further solid-liquid separation; the liquid material after centrifugation is sent to the first circulation tank 9, and the solid material is sent to the washing machine 12 for further washing and dechlorination; if the solid material after centrifugation in the first centrifuge 10 meets the requirements of landfill or comprehensive utilization, it is directly sent to the landfill or further recycled for resource utilization, part of the sodium chloride concentrate in the first circulation tank 9 is circulated to the stirring and dissolving kettle 2 through the first circulation pump 11, and the remaining part is sent to the salting section of the chlor-alkali plant for recycling;

[0012] In the third step, part of the washing circulating liquid in the second circulation tank 14 is sent to the washing liquid inlet of the water washing machine 12 through the third circulation pump 19 to wash the solid material after centrifugation in the first centrifuge 10; in addition, according to the water balance calculation, a certain amount of pure water is added to the washing liquid inlet of the water washing machine 12 from the first storage tank 16 through the third metering pump 17; the solid washed by the water washing machine 12 is sent to the second centrifuge 13 for solid-liquid separation, and the washing liquid is sent to the second circulation tank 14; the liquid material after centrifugation in the second centrifuge 13 is sent to the second circulation tank 14, and the solid material is landfilled or further recycled; the washing circulating liquid in the second circulation tank 14 is partially circulated into the stirring and dissolving kettle 2 through the second circulation pump 15, and the remaining part is circulated into the water washing machine 12 through the third circulation pump 19.

[0013] The stirring speed of the stirring dissolving kettle 2 is 800-1000 rpm, the hydraulic retention time is 1.5-2 hours, and a backwashing device is arranged at the bottom discharge port.

[0014] The fast stirring speed of the flocculation kettle 6 is 300-500 rpm, the slow stirring speed is 50-100 rpm, and a backwashing device is arranged at the bottom discharge port.

[0015] The clarification sedimentation tank 8 is a vertical flow sedimentation tank with a hydraulic retention time of 2 hours.

[0016] The first centrifuge 10 has a rotation speed of 4000-5000 rpm, a filter mesh number of 500-800 meshes, and a water content of the solid material after centrifugation of 20-25%.

[0017] The second centrifuge 13 has a rotation speed of 4000-5000 rpm, a filter mesh size of 500-800 meshes, and a water content of the solid material after centrifugation of 20-25%.

[0018] The operating conditions of the chlor-alkali industrial salt mud washing and dechlorination device are all normal temperature and pressure, and sealing treatment is adopted.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention reduces the sodium chloride content (dry basis) in salt mud from 5-10% to 1-2% by washing and dechlorination, and at the same time can reduce the total mass of the salt mud by more than 20%, thereby reducing the transportation and landfill costs of the salt mud, improving the quality of salt mud resource recovery products, and providing reliability for salt mud resource recovery.

[0021] 2. The present invention circulates the sodium chloride concentrate in the first circulation pool 9 as a dissolving liquid for salt mud, and uses part of the washing circulating liquid in the second circulation pool 14 as a dissolving liquid for salt mud and part as a washing liquid for the washing unit, which significantly reduces the amount of process water, can achieve 70-85% water saving, recycles the sodium chloride concentrate as a resource, and achieves zero discharge of process wastewater.

[0022] 3. The present invention adds a small amount of cationic PAM solution in the flocculation kettle 6, which increases the sedimentation rate of the salt mud, reduces the processing load of the subsequent solid-liquid separation equipment, reduces the energy consumption of the device, and reduces the operating cost of the salt mud dechlorination treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the device of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Example 1: The main components of the treated chlor-alkali industrial salt mud are shown in Table 1.

[0026] Table 1 Main components of chlor-alkali industrial salt mud

[0027] Components water Calcium carbonate Magnesium hydroxide Sodium chloride Clay and other components Mass content / % 29 33 6.5 10 21.5

[0028] Reference Figure 1A chlor-alkali industrial salt mud washing and dechlorination device comprises a stirring and dissolving kettle 2, wherein the upper feed port of the stirring and dissolving kettle 2 is connected to the outlet of a screw feeder 1; the washing circulating liquid inlet of the stirring and dissolving kettle 2 is connected to the second circulating pump 15 and the second circulating tank 14, and the second circulating tank 14 is connected to the washing liquid inlet of a washing machine 12 via a third circulating pump 19; the pure water inlet of the stirring and dissolving kettle 2 is connected to the first storage tank 16 via a first metering pump 18, and the first storage tank 16 is connected to the washing liquid inlet of the washing machine 12 via a third metering pump 17; the bottom outlet of the stirring and dissolving kettle 2 is connected to the washing liquid inlet of the washing machine 12 via a first outlet The material pump 3 is connected to the feed port of the flocculation kettle 6, the upper liquid inlet of the flocculation kettle 6 is connected to the second storage tank 4 through the second metering pump 5, and the bottom outlet of the flocculation kettle 6 is connected to the upper inlet of the clarification sedimentation tank 8 through the second discharge pump 7; the top liquid outlet of the clarification sedimentation tank 8 is connected to the first inlet of the first circulation tank 9, the bottom discharge port of the clarification sedimentation tank 8 is connected to the first centrifuge 10, the liquid outlet of the first centrifuge 10 is connected to the second inlet of the first circulation tank 9, the bottom outlet of the first circulation tank 9 is connected to the return port of the stirring and dissolving kettle 2 through the first circulation pump 11, and the bottom discharge may enter the salting section for reuse;

[0029] The solid discharge at the bottom of the first centrifuge 10 is landfilled or used to recover calcium and magnesium. The solid discharge at the bottom may be connected to a washing machine 12. The washing liquid outlet of the washing machine 12 is connected to the first inlet of a second circulation tank 14. The solid outlet of the washing machine 12 is connected to a second centrifuge 13. The liquid outlet of the second centrifuge 13 is connected to the second inlet of the second circulation tank 14. The solid discharge at the bottom of the second centrifuge 13 is landfilled or used to recover calcium and magnesium.

[0030] The process of using the chlor-alkali industrial salt mud washing and dechlorination device comprises the following steps:

[0031] The first step is to feed the chlor-alkali industrial salt mud into the stirring and dissolving tank 2 at 1.25 tons / h through the screw feeder 1, start the stirring device of the stirring and dissolving tank 2, and at the same time, feed part of the sodium chloride concentrate in the first circulation tank 9 into the stirring and dissolving tank 2 at 6.78 tons / h through the first circulation pump 11, and feed part of the washing circulation liquid in the second circulation tank 14 into the stirring and dissolving tank 2 at 1.27 tons / h through the second circulation pump 15;

[0032] In the second step, the fully stirred and dissolved material is discharged from the bottom of the stirring and dissolving tank 2, and is sent to the flocculation tank 6 at 9.30 tons / h through the first discharge pump 3. At the same time, the cationic PAM solution with a mass fraction of 5‰ in the second storage tank 4 is sent to the flocculation tank through the second metering pump 5 at 50kg / h, and the stirring device of the flocculation tank 6 is started, and the rapid stirring is performed for 5 minutes and the slow stirring is performed for 25 minutes; the flocculated material is discharged from the bottom of the flocculation tank 6, and is sent to the clarification sedimentation tank 8 at 9.35 tons / h through the second discharge pump 7 for free sedimentation. The supernatant after sedimentation for 2 hours is discharged from the clarification sedimentation tank 8. The top discharge flows into the first circulation tank 9 by gravity at 5.75 tons / h, and the settled solid materials are sent to the first centrifuge 10 at 3.60 tons / h from the bottom discharge of the clarification sedimentation tank 8 for further solid-liquid separation; the liquid materials after centrifugation are sent to the first circulation tank 9 at 2.56 tons / h, and the solid materials are sent to the washing machine 12 at 1.04 tons / h for further washing and dechlorination; part of the sodium chloride concentrate in the first circulation tank 9 is circulated to the stirring and dissolving kettle 2 through the first circulation pump 11 at 6.78 tons / h, and the remaining part is sent to the salt section of the chlor-alkali plant at 1.53 tons / h for recycling;

[0033] In the third step, part of the washing circulating liquid in the second circulation tank 14 is sent to the washing liquid inlet of the washing machine 12 through the third circulation pump 15 at 5.08 tons / h to wash the solid material after centrifugation in the first centrifuge 10; in addition, according to the system water balance calculation, 1.25 tons / h of pure water is added to the washing liquid inlet of the washing machine 12 from the first storage tank 16 through the third metering pump 17; the solid washed by the washing machine 12 is sent to the second centrifuge 13 at 1.32 tons / h for solid-liquid separation, and the washing liquid is sent to the second circulation tank 14 at 6.05 tons / h; 0.30 tons / h of liquid material after centrifugation in the second centrifuge 13 is sent to the second circulation tank 14, and the solid material is landfilled or further recycled; the washing circulating liquid in the second circulation tank 14 is circulated into the stirring dissolution kettle 2 through the second circulation pump at 1.27 tons / h, and the remaining part is circulated into the washing machine 12 through the third circulation pump 19 at 5.08 tons / h;

[0034] The stirring speed of the stirring dissolving kettle 2 is 800-1000 rpm, the hydraulic retention time is 1.5-2 hours, and a backwashing device is provided at the bottom discharge port;

[0035] The fast stirring speed of the flocculation kettle 6 is 300-500 rpm, the slow stirring speed is 50-100 rpm, and a backwashing device is provided at the bottom discharge port;

[0036] The clarification sedimentation tank 8 is a vertical flow sedimentation tank with a hydraulic retention time of 2h;

[0037] The first centrifuge 10 has a rotation speed of 4000-5000 rpm, a filter mesh of 500-800 mesh, and a water content of the solid material after centrifugation of 20-25%;

[0038] The second centrifuge 13 has a rotation speed of 4000-5000 rpm, a filter mesh number of 500-800 meshes, and a water content of the solid material after centrifugation of 20-25%, and a sodium chloride content of 1.0% (dry basis);

[0039] The sodium chloride mass concentration of the sodium chloride concentrate in the first circulation tank 9 is 85 g / L;

[0040] The operating conditions of the devices are all normal temperature and pressure, and sealing treatment is adopted.

[0041] The beneficial effects of this embodiment are:

[0042] (1) The pure water consumption of this embodiment is small, which reduces the water cost;

[0043] (2) This embodiment produces a small amount of sodium chloride concentrate, and the concentration of the sodium chloride concentrate is high, which is convenient for subsequent recycling and utilization. It is more suitable for chlor-alkali plants with a small additional demand for sodium chloride concentrate;

[0044] (3) In this embodiment, the chlor-alkali industrial salt mud is further washed with low-chlorine washing liquid, thereby reducing the content of sodium chloride in the salt mud after dechlorination, which is more conducive to the further resource utilization of the dechlorinated salt mud.

[0045] In Example 2, the main components of the treated chlor-alkali industrial salt mud are still as shown in Table 1. The structure of the chlor-alkali industrial salt mud washing and dechlorination device in this example is the same as that in Example 1.

[0046] The process of using the chlor-alkali industrial salt mud washing and dechlorination device comprises the following steps:

[0047] The first step is to feed the chlor-alkali industrial salt mud into the stirring and dissolving kettle 2 at 1.25 tons / h through the screw feeder 1, start the stirring device of the stirring and dissolving kettle 2, and at the same time, feed part of the sodium chloride concentrate in the first circulation tank 9 into the stirring and dissolving kettle 2 at 5.68 tons / h through the first circulation pump 11, and according to the system water balance calculation, add 2.09 tons / h of pure water from the first storage tank 16 to the stirring and dissolving kettle 2 through the first metering pump 18;

[0048] In the second step, the fully dissolved material is discharged from the bottom of the stirring and dissolving tank 2, and is sent to the flocculation tank 6 through the first discharge pump 3 at 9.02 tons / h. At the same time, the cationic PAM solution with a mass fraction of 5‰ in the second storage tank 4 is sent to the flocculation tank through the second metering pump 5 at 50kg / h, and the stirring device of the flocculation tank 6 is started, and the rapid stirring is performed for 5 minutes and the slow stirring is performed for 25 minutes; the flocculated material is discharged from the bottom of the flocculation tank 6, and is sent to the clarification sedimentation tank 8 through the second discharge pump 7 at 9.07 tons / h for free sedimentation. The supernatant after sedimentation for 2 hours is discharged from the clarification sedimentation tank 8. The top discharge flows into the first circulation tank 9 by gravity at 5.57 tons / h, and the settled solid materials are sent to the first centrifuge 10 at 3.50 tons / h from the bottom discharge of the clarification sedimentation tank 8 for further solid-liquid separation; the liquid materials after centrifugation are sent to the first circulation tank 9 at 2.48 tons / h, and the solid materials are landfilled or further recycled at 1.02 tons / h; part of the sodium chloride concentrate in the first circulation tank 9 is circulated to the stirring and dissolving kettle 2 at 5.68 tons / h through the first circulation pump 11, and the remaining part is sent to the salt section of the chlor-alkali plant at 2.37 tons / h for recycling;

[0049] The stirring speed of the stirring dissolving kettle 2 is 800-1000 rpm, the hydraulic retention time is 1.5-2 hours, and a backwashing device is provided at the bottom discharge port;

[0050] The fast stirring speed of the flocculation kettle 6 is 300-500 rpm, the slow stirring speed is 50-100 rpm, and a backwashing device is provided at the bottom discharge port;

[0051] The clarification sedimentation tank 8 is a vertical flow sedimentation tank with a hydraulic retention time of 2h;

[0052] The first centrifuge 10 has a rotation speed of 4000-5000 rpm, a filter mesh number of 500-800 meshes, and a water content of the solid material after centrifugation of 20-25%, and a sodium chloride content of 1.8% (dry basis);

[0053] The sodium chloride mass concentration of the sodium chloride concentrate in the first circulation tank 9 is 50 g / L;

[0054] The operating conditions of the chlor-alkali industrial salt mud washing and dechlorination device are all normal temperature and pressure, and sealing treatment is adopted.

[0055] The beneficial effects of this embodiment are:

[0056] (1) Compared with Example 1, this embodiment simplifies the process flow, greatly reducing the fixed asset investment cost and process operation cost;

[0057] (2) The concentration of the sodium chloride concentrate produced in this embodiment is low, and the process has great operational flexibility.

[0058] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by those skilled in the art shall all fall within the scope of protection determined by the claims of the present invention.

Claims

1. A chlor-alkali industrial salt mud washing and dechlorination device, comprising a stirring dissolving kettle (2), characterized in that: The upper feed port of the stirring and dissolving kettle (2) is connected to the outlet of the screw feeder (1); the washing circulating liquid inlet of the stirring and dissolving kettle (2) is connected to the second circulation tank (14) via the second circulation pump (15), the second circulation tank (14) is connected to the washing liquid inlet of the water washer (12) via the third circulation pump (19), part of the washing circulating liquid in the second circulation tank (14) is used as the dissolving liquid of the salt mud, and part of it is used as the washing liquid of the water washer (12); the pure water inlet of the stirring and dissolving kettle (2) is connected to the first storage tank (16) via the first metering pump (18), the first storage tank (16) is connected to the washing liquid inlet of the water washer (12) via the third metering pump (17); the bottom outlet of the stirring and dissolving kettle (2) is connected to the feed port of the flocculation kettle (6) via the first discharge pump (3), the flocculation kettle (6) The upper liquid inlet is connected to the second storage tank (4) through a second metering pump (5), the cationic PAM solution in the second storage tank (4) is fed into the flocculation kettle (6) through the second metering pump (5), the bottom outlet of the flocculation kettle (6) is connected to the upper inlet of the clarification sedimentation tank (8) through a second discharge pump (7); the top liquid outlet of the clarification sedimentation tank (8) is connected to the first inlet of the first circulation tank (9), the bottom discharge outlet of the clarification sedimentation tank (8) is connected to the first centrifuge (10), the liquid outlet of the first centrifuge (10) is connected to the second inlet of the first circulation tank (9), the bottom outlet of the first circulation tank (9) is connected to the return port of the stirring dissolution kettle (2) through a first circulation pump (11), the bottom discharge or enters the salting section for reuse, and the sodium chloride concentrate in the first circulation tank (9) is circulated as a dissolving liquid for salt mud; The solid discharge at the bottom of the first centrifuge (10) is landfilled or calcium and magnesium are recovered. The solid discharge at the bottom is connected to a washing machine (12). The washing liquid outlet of the washing machine (12) is connected to the first inlet of the second circulation tank (14). The solid outlet of the washing machine (12) is connected to the second centrifuge (13). The liquid outlet of the second centrifuge (13) is connected to the second inlet of the second circulation tank (14). The solid discharge at the bottom of the second centrifuge (13) is landfilled or calcium and magnesium are recovered.

2. A process for washing and dechlorinating a chlor-alkali industrial salt mud device according to claim 1, characterized in that: The following steps are involved: The first step is to feed the chlor-alkali industrial salt mud into the stirring and dissolving kettle (2) through the screw feeder (1), start the stirring device of the stirring and dissolving kettle (2), and at the same time, feed part of the sodium chloride concentrate in the first circulation tank (9) into the stirring and dissolving kettle (2) through the first circulation pump (11), and feed part of the washing circulation liquid in the second circulation tank (14) into the stirring and dissolving kettle (2) through the second circulation pump (15); in addition, according to the water balance calculation, a certain amount of pure water is added from the first storage tank (16) into the stirring and dissolving kettle (2) through the first metering pump (18); In the second step, the material that has been stirred and dissolved sufficiently is discharged from the bottom of the stirring and dissolving tank (2) and sent to the flocculation tank (6) through the first discharge pump (3). At the same time, the cationic PAM solution in the second storage tank (4) is sent to the flocculation tank (6) through the second metering pump (5). The stirring device of the flocculation tank (6) is started, and the material is stirred rapidly for 5 minutes and slowly stirred for 25 minutes. The flocculated material is discharged from the bottom of the flocculation tank (6) and sent to the clarification sedimentation tank (8) through the second discharge pump (7) for free sedimentation. The supernatant after sedimentation is discharged from the top of the clarification sedimentation tank (8) and flows into the first circulation tank ( 9), the solid material after sedimentation is discharged from the bottom of the clarification sedimentation tank (8) and sent to the first centrifuge (10) for further solid-liquid separation; the liquid material after centrifugation is sent to the first circulation tank (9), and the solid material is sent to the washing machine (12) for further washing and dechlorination; if the solid material after centrifugation in the first centrifuge (10) meets the requirements of landfill or comprehensive utilization, it is directly sent to the landfill or further recycled for resource utilization; part of the sodium chloride concentrate in the first circulation tank (9) is circulated to the stirring dissolving kettle (2) through the first circulation pump (11), and the remaining part is sent to the salting section of the chlor-alkali plant for recycling; In the third step, part of the washing circulating liquid in the second circulation tank (14) is sent to the washing liquid inlet of the water washer (12) through the third circulation pump (19) to wash the solid material after centrifugation in the first centrifuge (10); in addition, according to the water balance calculation, a certain amount of pure water is added from the first storage tank (16) to the washing liquid inlet of the water washer (12) through the third metering pump (17); the solid material after washing in the water washer (12) is sent to the second centrifuge (13) for solid-liquid separation, and the washing liquid is sent to the second circulation tank (14); the liquid material after centrifugation in the second centrifuge (13) is sent to the second circulation tank (14), and the solid material is landfilled or further recycled; part of the washing circulating liquid in the second circulation tank (14) is circulated into the stirring dissolution kettle (2) through the second circulation pump (15), and the remaining part is circulated into the water washer (12) through the third circulation pump (19).

3. The process according to claim 2, characterized in that: The stirring speed of the stirring dissolving kettle (2) is 800-1000 rpm, the hydraulic retention time is 1.5-2 h, and a backwashing device is provided at the bottom discharge port.

4. The process according to claim 2, characterized in that: The fast stirring speed of the flocculation kettle (6) is 300-500 rpm, the slow stirring speed is 50-100 rpm, and a backwashing device is provided at the bottom discharge port.

5. The process according to claim 2, characterized in that: The clarification sedimentation tank (8) is a vertical flow sedimentation tank with a hydraulic retention time of 2 h.

6. The process according to claim 2, characterized in that: The first centrifuge (10) has a rotation speed of 4000-5000 rpm, a filter mesh size of 500-800 meshes, and a moisture content of the solid material after centrifugation of 20-25%.

7. The process according to claim 2, characterized in that: The second centrifuge (13) has a rotation speed of 4000-5000 rpm, a filter mesh size of 500-800 mesh, and a water content of the solid material after centrifugation of 20-25%.

8. The process according to claim 2, characterized in that: The operating conditions are normal temperature and pressure, and all components are sealed.

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